352 BOTANICAL GAZETTE [way 
not the case, and so it seems highly probable at least that the stimu- 
lating factor of bog waters is not the hydrogen ion. 
Further, a comparison of the acidity figures with the response of 
the plant in the different waters shows clearly that the former data 
could not be used as a criterion for the prediction of the latter. This 
is clearly brought out in the following list, in which the acidity figures 
are arranged in order of their magnitude, with the responses occurring 
in the corresponding water placed after each. Alkalinity 0.0015”, F; 
acidity 0.0002”, F; 0.0003n, F, $P,P; o.cco4n, F,P; 0.00048”, 
P; 0.0005”, F; 0.0008n, F; 0.0o1m, F; 0.0015”, P; o.co1gn, $P; 
0.0022n, 4P,P; 0.0026n, P; 0.00332, P; 0.0038”, P. The lower 
acidities appear to produce both filaments and palmella, the 
igher ones only palmella. This would seem to indicate that, while 
high acidity is always accompanied by the presence of the stimulating 
substances, these substances are not necessarily accompanied by 
high acidity. 
Boiling the stimulating waters for five or ten minutes and then 
rediluting to the original volume with redistilled water decreases their 
acidity from 30 to 50 per cent., but appears not to alter their stim- 
ulating power. Apparently the active substances are not volatile 
at 100° C. Diluting the Ann Arbor samples, and also those from 
Tom’s River numbered 2, 3, and 4, with distilled water or with weak 
nutrient solution, decreases the toxic effect, and this effect practically 
disappears when the water has been diluted to twice its volume. 
This is evidence that the stimulating substances are present in 
extremely small amount. 
The relation of the source of these waters and the type of vege- 
tation growing therein to the physiological properties exhibited 
toward Stigeoclonium throws some light on the general problem of 
the xerophilous character of bog plants. The drained swamps of 
the Hackensack valley are not in any sense bogs. In many places, 
however, are found spots where Sphagnum has taken a foothold in 
small pools. Eriophorum, Typha, and some other semi-xerophilous 
plants are also found here. The water samples studied were taken 
from such places, and the experiments show that they possess the 
toxic property to a considerable degree. The data for this broad 
area of swamps are averaged from a large number of samples taken 
near Englewood and Closter, N. J., as well as from the western slope 
SE ER Te ited iin ee 
a a a A a a a a a a At 
